Those of ordinary skill in the art will appreciate that the oil industry often uses three-dimensional (3D) visualization to showcase its exploitation of the latest high-tech developments. (As used herein, the term “visualization” is intended to encompass a process involving the computer processing, transformation, and visual/graphical display of measured or simulated data to facilitate its interpretation.) Visualization has become a well-established planning and analytical tool for the geological and geophysical (G&G) segment of the industry. Benefits extend beyond technical issues, as communal visualization has promoted multi-disciplinary discussion and created opportunities to bring people together and improve the dynamics of exploration and production (E&P) teams by providing clarity in the face of the ever-increasing amount of data that forms the modem well construction process.
Similar success is being achieved in drilling. Early applications focused on well placement in complex reservoirs, and directional drilling to control well tortuosity and avoid collisions on multi-well platforms. More recent applications use 3D visualization to address drilling problems and link drilling operational data to earth models. Countless other drilling prospects should exist, especially considering that “making hole” occurs out of sight, miles below the earth's surface.
One reason that this visualization of the wellbore and vicinity around the wellbore is important is that the operator can immediately see the impact that certain changes have on other wellbore parameters. For example, if one parameter is adjusted from the surface or if a different fluid is added to the wellbore, the operator can see if that change has affected the hydraulics within the wellbore as well as the magnitude of the resulting effect on the hydraulic parameters within the wellbore. It certainly is possible that in the not-too-distant future, a driller controlling the brake with a joystick could use a different joystick to visually navigate to places in the well where a powerful computer has simulated an existing or pending drilling problem
In the prior art, downhole visualization has focused principally on the trajectory of the borehole, particularly with the ever-increasing popularity of directional drilling. Knowing the precise location of the borehole at all points along its length is critical to ensure that the drilling operation succeeds ultimately in the borehole arriving at the desired production region.
Downhole video is a proven telepositioning method for mechanical inspection, fishing operations, and problem investigation in a wellbore. Unfortunately, downhole video cannot be used during drilling, because (a) nearly all drilling fluids are opaque; (b) normal drilling operations would have to be suspended; and (c) the drill string would interfere with camera operations.
Videos taken of simulated wellbores in the laboratory, despite temperature and pressure shortcomings, have contributed significantly to the industry's understanding of downhole behavior, especially hole cleaning and barite sag. Remarkable footage captured through transparent, inclined flow loops have documented the impact of different parameters on hole-cleaning efficiency, including hole angle, annular velocity, pipe eccentricity and rotation, low-shear-rate viscosity, flow regime, and avalanching cuttings beds. Video has also helped validate the field success with drilling horizontal wells at some sites with Theologically engineered bio-polymer drill-in fluids, a hole-cleaning concept that was contrary to industry thinking at the time. Additionally, laboratory studies based on extensive video imaging helped convince the industry that barite sag was primarily a dynamic settling problem and not the static problem as previously thought.
Nevertheless, video examination of actual wellbores is not a practical alternative, meaning that other means must be employed to analyze dynamic parameters of the interior of a wellbore.
Outside of the oil industry, video has long been a mainstay to view objects not easily accessible. The medical field is perhaps the best known, and the colonoscopy is an excellent analogy to downhole video technology. Recent technological advancements have made it possible to perform a non-invasive procedure called a “virtual” colonoscopy. The virtual colonoscopy process involves performing a spiral (or helical) computer-aided tomography (CAT) scan, wherein a rotating x-ray machine follows a spiral path around the body. A high-powered computer uses the x-ray data to create detailed cross-sectional pictures of the body. The high-resolution, 2D pictures are then assembled like slices in a loaf of bread to construct a detailed, 3D image of the colon lining suitable for thorough analysis by the doctor.
Virtual images created for medical use invariably are based on measured data. Unfortunately, detailed data required along a well path cannot be measured with current technology. The alternative is to simulate the downhole drilling process with appropriate models for critical information that is not yet measured. Logically, the accuracy of the models is important.
To address this problem, computer applications have been developed for simulating the internal environmental dynamics within wellbores based on measured or modeled data about the well. Advanced software has emerged that considers, among other things, the effects of temperature and pressure on density and rheology of the drilling fluid. Numerous commercially-available examples of such analysis applications are known in the art. An interesting aspect of such programs is that the modules created for calculating equivalent static densities (ESDs), for example, are based on numerical integration of short wellbore segments. This approach has set the stage for using techniques involving finite difference analysis for other calculations. Generally speaking, hydraulics applications function to take a number of dynamic, depth-varying parameters for a wellbore (and drill string) as inputs to provide as output one or more indicators of well performance and behavior. Additionally, hydraulics applications that incorporate time-varying parameters for a wellbore are also available. These time varying parameters may take the form of transient data, representing the evolution of well parameters over time, or real-time data, which includes measured well parameters, as the name suggests, in real time.
Accuracy is a serious issue regarding downhole simulation. Oftentimes, measured data or a combination of simulated and measured data can be used to understand the internal environmental dynamics in the wellbore environment. Currently much of these data are presented in traditional two dimensional graphs or in data tables. However, in many cases, large data sets make this cumbersome or mentally impossible. This difficulty is compounded greatly when moving from steady state data to transient and real-time data. Thus there remains an on-going need for methods of viewing and analyzing depth-varying and/or time-varying data sets in a visually appealing manner.